500300 Rev. U
Menu Operations
4-11
that the spaces between each recorded character and the gaps between the newly
recorded data blocks are perfectly erased. Unfortunately, poorly maintained drives
sometimes do a poor job of erasing previously recorded data. If any previously
recorded data remains on the tape, it can cause erroneous characters to be detected
in a block, or erroneous blocks to be detected in the gaps between the correctly
written blocks. Raising the read threshold level may prevent these error characters
from being recognized. However, the downside of raising the read threshold, is that
a dropout that can normally be read without error may now cause a Hard Error
(HER).
Any of the above three alternative read strategies could allow a tape with the
indicated problems to be read successfully. However, these alternatives could also
cause an otherwise good tape to be read unsuccessfully. The SEISMIC configuration
item should be set to OFF to provide the optimum decoding performance for
normally–written tapes. If a tape is encountered that cannot be read successfully
with the SEIS-MIC option turned OFF, then try re-reading the tape with the option
turned ON. Using the SEISMIC option will not harm the drive or the tape.
The SEISMIC option affects Qualstar Model 3410/12 and 3416/18 tape drives. It only
affects the reading of 800 CPI (NRZI) tapes. When activated, the feature eliminates
the reporting of Hard Errors (HERs) caused by the CRCC and LRCC characters
found at the end of each NRZI data block.
The SEISMIC configuration option has two possible values: NO and YES. Note that
this menu item will also appear on models 3413/14, but it will have no effect on
these drives, as they do not read 800 CPI (NRZI) tapes.
The SEISMIC options have the following effects when reading 800 CPI (NRZI) tapes:
NO
- The drive reads 800 CPI (NRZI) tapes as it always has, checking the CRCC and
LRCC bytes on the tape against those accumulated during the reading of the block.
If the written values do not agree with the accumulated values, a Hard Error (HER)
is reported to the interface.
YES
- The drive suppresses the reporting of Hard Errors (HERs) due to the CRCC or
LRCC check bytes not matching those accumulated by the tape drive during the
reading of a block. A parity error will still cause the drive to report a Hard Error
(HER).
4.3.2.21
HEAD CLEAN: (Default = 25)
This parameter represents the equivalent number of full 2400-foot reels of tape (run
from BOT to EOT to BOT) that will cause the drive to display the head-cleaning
reminder. The actual number of feet which have passed the head since the head
cleaning odometer was last reset can be calculated by multiplying 4800 feet times
the value of this parameter. Chapter 5 describes how to clean the head and
paragraph describes how to reset the head cleaning odometer.
4.3.2.22
PE GAIN: (Default = Auto)
Qualstar has developed an adaptive automatic gain system for model 341X tape
drives that enhances read reliability in the PE mode for tapes that produce a
